The present invention relates to hydroxam ate derivatives of non-steroidal anti-inflammatory drugs (NSAIDs). Invention compounds have multiple uses, for example, as prodrugs of NSAIDs, dual inhibitors of cyclooxygenase (COX) and 5-lipoxygenase (5-LO), as anticancer agents (through promoting apoptosis and/or inhibiting matrix metalloproteinase enzymes (MMP)), and the like. In another aspect, the present invention relates to formulations containing invention compounds and methods for use thereof.
Despite the advent of modem pharmaceutical technology, many drugs still possess untoward toxicities which often limit the therapeutic potential thereof. For example, although non-steroid anti-inflammatory drugs (NSAIDs) are a class of compounds which are widely used for the treatment of inflammation, pain and fever, NSAIDs (e.g., naproxen, aspirin, ibuprofen and ketoprofen) can cause gastrointestinal ulcers, a side-effect that remains the major limitation to the use of NSAIDs (see, for example, J. L. Wallace, in Gastroenterol. 112:1000-1016 (1997); A. H. Soll et al., in Ann Intern Med. 114:307-319 (1991); and J. Bjarnason et al., in Gastroenterol. 104:1832-1847 (1993)).
There are two major ulcerogenic effects of NSAIDs: (1) irritant effects on the epithelium of the gastrointestinal tract and (2) suppression of gastrointestinal prostaglandin synthesis. In recent years, numerous strategies have been attempted to design and develop new NSAIDs that reduce the damage to the gastrointestinal tract. These efforts, however, have largely been unsuccessful. For example, enteric coating or slow-release formulations designed to reduce the topical irritant properties of NSAIDs have been shown to be ineffective in terms of reducing the incidence of clinically significant side effects, including perforation and bleeding (see, for example, D. Y. Graham et al., in Clin. Pharmacol. Ther. 38:65-70 (1985); and J. L. Carson, et al., in Arch. Intern. Med., 147:1054-1059 (1987)).
It is well recognized that aspirin and other NSAIDs exert their pharmacological effects through the non-selective inhibition of cyclooxygenase (COX) enzymes, thereby blocking prostaglandin synthesis (see, for example, J. R. Van in Nature, 231:232-235 (1971)). There are two types of COX enzymes, namely COX-1 and COX-2. COX-1 is expressed constitutively in many tissues, including the stomach, kidney, and platelets, whereas COX-2 is expressed only at the site of inflammation (see, for example, S. Kargan et al. in Gastroenterol., 111:445-454 (1996)). The prostaglandins whose production is mediated by COX-1 are responsible for many of their physiological effects, including maintenance of gastric mucosal integrity.
Many attempts have been made to develop NSAIDs that only inhibit COX-2, without impacting the activity of COX-1 (see, for example, J. A. Mitchell et al., in Proc. Natl. Acad. Sci. USA 90:11693-11697 (1993); and E. A. Meade et al., in J. Biol. Chem., 268:6610-6614 (1993)). There are several NSAIDs presently on the market (e.g., rofecoxib and celecoxib) that show marked selectivity for COX-2 (see, for example, E. A. Meade, supra.; K. Glaser et al., in Eur. J. Pharmacol. 281:107-111 (1995) and Kaplan-Machlis, B., and Klostermeyer, B S in Ann Pharmacother. 33:979-88, (1999)). These drugs appear to have reduced gastrointestinal toxicity relative to other NSAIDs on the market.
On the basis of encouraging clinical as well as experimental data, the development of highly selective COX-2 inhibitors appears to be a sound strategy to develop a new generation of anti-inflammatory drugs. However, the physiological functions of COX-1 and COX-2 are not always well defined. Thus, there is a possibility that prostagladins produced as a result of COX-1 expression may also contribute to inflammation, pain and fever. On the other hand, prostagladins produced as a result of COX-2 expression have been shown to play important physiological functions, including the initiation and maintenance of labor and in the regulation of bone resorption (see, for example, D. M. Slater et al., in Am. J. Obstet. Gynecol., 172:77-82 (1995); and Y. Onoe et al., in J. Immunol. 156:758-764 (1996)), thus inhibition of this pathway may not always be beneficial. Considering these points, highly selective COX-2 inhibitors may produce additional side effects above and beyond those observed with standard NSAIDs, therefore such inhibitors may not be highly desirable.
Indeed, recent studies with first generation COX-2 inhibitors reveal that arthritic patients treated with rofecoxib had a five-fold higher risk of heart attack, compared to patients treated with naproxen (Wall St. Jrnl, 5/1/10). Thus, like aspirin, naproxen appears to exert cardioprotective effects, while selective COX-2 inhibitors do not. The reason why selective COX-2 inhibitors appear to cause elevated risk of heart attack has been studied (see Y. Cheng et al., in Science 296(19): 539-541 (2002)). Because of this potentially serious side effect of selective COX-2 inhibitors, there is still a need in the art for new NSAIDs (or derivatives thereof) with reduced gastrointestinal (GI) side effects.
The enzyme 5-LO is an iron-containing dioxygenase (see M. Gibian et al., in Bio-Org. Chem. 1:117 (1977)) that catalyzes the first step of the biochemical pathway to convert arachidonic acid to leukotrienes. Leukotrienes are important mediators in inflammatory diseases including asthma, arthritis, psoriasis and allergy (see P, Sirois in Adv. Lipid Res. 21:79 (1995)). Inhibition of 5-LO is an important avenue for therapeutic treatment of these diseases.
Hydroxamates are well known to form strong complexes with transition metal ions including iron (see H. Kiehl in The Chemistry And Biochemistry Of Hydroxyamic Acids, Karger, Basel (1982)). Some hydroxamates have shown good inhibitory activity against 5-LO (See, for example, J. B. Summers et al., in J. Med. Chem. 33:992-998(1990); A. O. Stewart et al., in J. Med. Chem. 40: 1955-1968 (1997); and T. Kolasa et al., in J. Med. Chem. 40:819-824 (1997)).
As described above, NSAIDs are relatively non-specific COX inhibitors, that commonly cause adverse effects, especially, gastrointestinal ulceration. A compound which provides inhibitory activities against both COX and 5-LO may provide improved anti-inflammatory activity with reduced NSAID-related side effects. Indeed, several research groups have studied dual inhibitors containing an hydroxamic acid group in their molecules (see T. Hidaka et al., in Jpn. L. Pharmacol, 36: 77-85 (1984); H. Ikuta et al., in J. Med. Chem. 30:1995-1998 (1987); S. Wong et al., in Agents Actions 37:90-98(1992); P. C. Unangst et al., in J. Med. Chem. 37: 322-328 (1994); R. Richard L. et al., in J. Med. Chem. 39:246-252 (1996); and M. Inagak et al., in J. Med. Chem. 43:2040-2048 (2000)). In those studies, the molecule as an intact entity is designed to provide inhibitory activity against both COX and 5-LO. In general, however, these approaches have not proven to be very effective.
Accordingly, there remains a need in the art for compounds which are more effective for the treatment of various inflammatory diseases with reduced NSAID-related side effects.
From experimental models of carcinogenesis, it has become apparent that NSAIDs have cancer chemopreventive properties, although their application to human cancer and the extent of their benefits in the clinic is presently a matter of intensive investigation (see G. A. Piazza et al., in Cancer Research, 57: 2452-2459 (1997)). While the results have been explained by reference to different mechanisms, many experiments have shown that NSAIDs have the potential to induce apoptosis (see, for example, K. Lundholm et al., in Cancer Research 54:5602-5606(1994); B. M. Bayer et al., in Biochem. Pharma. 28:441-443(1979), and in The J. Pharma. And Experiment. Therapeutics 210:106 (1979); N. N. Mahmoud et al., in Carcinogenesis 19:876-91(1998); V. Hial et al., in The J. Pharma. And Experiment. Therapeutics 202:446-454 (1977); B. Bellosillo et al., in Blood 92: 1406-1414(1998); N. E. Hubbard et al., in Cancer letters 43:111-120(1988); L. Qiao et al., in Biochem. Pharma. 55:53-64(1998); and S. J. Shiffet al., in Experimental Cell Res. 222: 179-188(1996)).
Matrix metalloproteinases (MMPs), also called matrixines, are a family of structurally related zinc-containing enzymes that mediate the breakdown of connective tissue and are therefore targets for therapeutic inhibitors in many inflammatory, malignant and degenerative diseases (see M. Whittaker et al., in Chem. Rev. 99: 2735-2776 (1999)). Consequently a considerable amount of effort has been invested in designing orally active MMP inhibitors with the expectation that such agents will be able to either halt or slow the progression of diseases such as osteoarthritis, tumor metastasis, and corneal ulceration (see M. Cheng et al., 43: 369-380 (2000)). Since hydroxamate can form strong complexes with transition state metal ions including zinc, the vast majority of MMP inhibitors incorporate an hydroxamate group as the zinc binding ligand (see M. Whittaker et al., in Chem. Rev. 99: 2735-2776 (1999); B. Barlaam et al., 42:4890-4908(1999)).
Accordingly, incorporation of the hydroxamate functionality into pharmacologically active compounds may provide novel compounds with enhanced anti-cancer activity and/or a reduced side effect profile.
In accordance with the present invention, there are provided novel chemical entities which have multiple utilities, e.g., as prodrugs of NSAIDs; as dual inhibitors of cyclooxygenase (COX) and 5-lipoxygenase (5-LO); as anticancer agents (through promoting apoptosis and/or inhibiting matrix metalloproteinases (MMPs), and the like. Invention compounds comprise a non steroidal anti-inflammatory agent (NSAID), covalently linked via a suitable linker, to a hydroxamate. Invention compounds are useful for a variety of applications, such as, for example, treating inflammation and inflammation-related conditions; enhancing anti-inflammatory activity of NSAIDs, reducing the side effects associated with administration of anti-inflammatory agents; as anticancer agents (through promoting apoptosis and/or inhibiting matrix metalloproteinases (MMPs)), and the like.
Invention compounds are conjugate compounds of NSAIDs and hydroxamates, covalently linked in such a way that they can be broken into two individual molecules in the circulation system to provide their own inhibitory activity against COX and 5-LO, respectively.
The NSAID component of invention compounds is capable of inducing apoptosis and the hydroxamate component is capable of inhibiting MMP. The two components are simultaneously administered as they are covalently linked, which in due course produces the original two components upon exposure to enzyme(s) in the circulatory system. Upon cleavage, the individual components are capable of contributing their cancer preventive activity with reduced NSAID-related side effects.